Decreased lactose percentage in milk associated with quarter health disorder and hyperketolactia, a proxy for negative energy balance, in dairy cows.

Several studies have described variations in lactose content (LC) in dairy cows during udder quarter health disorder or negative energy balance (NEB). However, their joint effects on LC have never been described. This was the aim of a longitudinal observational study performed on 5 Quebec dairy farms using automatic milking systems. Quarter milk samples were collected every 14 d from 5 to 300 DIM. Quarter health status was described by combining SCC level (SCC- or SCC+: < or ≥100,000 cells/mL) and infectious status (Patho- or Patho+: presence or absence of pathogens on a milk culture). Cows with NEB in early lactation (DIM <70) were identified using milk ß-hydroxybutyrate (BHB) content: 0.15 mM = BHB-; 0.15 - 0.19 mM = BHB+; > 0.19 mM = BHB++. A total of 14,505 quarter cisternal milk samples were collected from 380 lactating cows. The quarter LC was analyzed using a mixed linear regression model with the following fixed effects: quarter health status, parity, time interval between last milking and sampling, quarter milk yield (in kg/d), DIM, and herd. A random quarter intercept with a repeated measures correlation structure and a cow random intercept were also specified. The LC of SCC+ quarters was lower (-0.17 ± 0.013% pts) compared with LC of SCC- quarters for both primiparous and multiparous cows. Over the 162 bacterial species identified, only 8 species had a prevalence greater than 4.0%, and just 5 of them were associated with a reduction in LC: Staphylococcus aureus, Staph. chromogenes, Streptococcus dysgalactiae, Staph. epidermidis, and Staph. simulans. Cows identified as BHB+ and BHB++ in early lactation had a lower LC (-0.05 ± 0.019% and -0.13 ± 0.020% pts, respectively) compared with BHB- cows. For BHB++ cows, in both parity groups the decrease in LC (-0.20 ± 0.025% pts) was higher in SCC+ quarters compared with SCC- quarters. Moreover, the additive effect of the quarter health status and NEB on milk LC was greater with larger increases in BHB. Our findings highlight the necessity to jointly take into consideration both quarter health status and milk BHB concentration when using LC as a biomarker for NEB.

Biosecurity adoption in Québec dairy farms: results from a risk assessment questionnaire analyzed using conventional and unsupervised artificial intelligence methods.

This study documents the current state of biosecurity on dairy farms in Québec following the implementation of a mandatory biosecurity risk evaluation that was part of the proAction® accreditation program developed by Dairy Farmers of Canada. Using a cross-sectional design, 3,825 risk assessment questionnaires completed between 2018 and 2021 were extracted from Vigil-Vet database, which is a software utilized by veterinarians for conducting the proAction® risk assessment. Descriptive statistics were used to summarize the practices adopted by dairy producers. Additionally, multiple correspondence analysis was used to explore the association between the diseases of most concern and the adoption of biosecurity practices. Moreover, we used a hierarchical cluster analysis on principal components to identify distinct patterns of biosecurity practices among dairy producers. This analysis enabled the identification of typologies or clusters of farms based on the specific biosecurity practices they currently employ. The results of the descriptive statistics indicated that mastitis was the disease of most concern for most dairy farmers (40%). Moreover, given that only 10% of the 2,237 dairy farmers who acquired animals adhered to quarantine practices, there seems to be a need for improved implementation of biosecurity measures aimed at restricting the introduction of diseases when introducing new animals. Conversely, cleaning stalls and health equipment were adequately addressed by 95% and 86% of dairy producers, respectively. The multiple correspondence analysis indicated no significant association between the disease of most concern and the farm's biosecurity profile, except for respondents who identified digital dermatitis as their disease of most concern. Through the hierarchical cluster analysis, 3 clusters were identified among 3,581 farms: (1) Cluster 1 included farms with good management of sick animals; (2) Cluster 2 included farms with good management of young animals; and (3) Cluster 3 included farms with poor management of sick animals and young animals. Our study makes an important contribution by providing valuable insights into the biosecurity practices currently adopted on Québec dairy farms. It establishes a baseline for assessing progress in biosecurity practices adoption and serves as a reference point for future evaluations. In addition, these findings play a key role in monitoring the effectiveness of interventions aimed at improving biosecurity on dairy farms. By making use of this knowledge, stakeholders can make informed decisions that prioritize animal health, increase productivity, and ensure sustainability of the dairy industry.

Associations among antimicrobial use, calf management practices, and antimicrobial resistance in Escherichia coli from a pooled fecal sample in calves on Canadian dairy farms: a cross-sectional study.

The objective of this cross-sectional study was to determine associations between calf management practices, the number of antimicrobial treatments, and antimicrobial resistance in pre-weaned heifers on Canadian dairy farms. A composite of 5 fecal samples from pre-weaned calves was collected from 142 dairy farms in 5 provinces and analyzed for phenotypic antimicrobial susceptibility with the microbroth dilution method. Questionnaires were used to capture herd characteristics and calf management practices used on the farm. Calf treatment records were collected during the farm visits. Escherichia coli was isolated from all 142 fecal samples with the highest resistance to tetracycline (41%), followed by sulfisoxazole (36%), streptomycin (32%), chloramphenicol (28%), ampicillin (16%), trimethoprim-sulfamethoxazole (15%), ceftriaxone (4.2%), cefoxitin (2.8%), amoxicillin-clavulanic acid (2.1%), ciprofloxacin (2.1%), nalidixic acid (2.1%), azithromycin (1.4%), and gentamicin (1.4%). Multidrug resistance was observed in 37% of E. coli isolates. Three-quarters of farms used fresh colostrum as the most common type of colostrum fed to calves. Colostrum quality was checked on 49% of farms, but the transfer of passive immunity was only checked on 32% of farms in the last 12 mo. Almost 70% of farms used straw or hay or a combination as the bedding material for calves. Among the 142 farms, a complete set of calf records were collected from 71 farms. In a multivariable logistic regression model, farms with ≥1.99 - 32.57 antimicrobial treatments/calf-year were 3.2 times more likely to have multidrug resistant E. coli in calf feces compared farms with <1.99 antimicrobial treatments/calf-year. Farms using hay or straw beddings were 5.1 times less likely to have multidrug resistant E. coli compared with those with other bedding materials including shavings or sawdust. Bedding management practices on farms may need to be investigated to reduce the potential impact on disseminating multidrug resistant bacteria.

Risk factors for Salmonella Dublin on dairy farms in Ontario, Canada.

Salmonella Dublin is an emerging pathogen on dairy farms in Canada. In Ontario, Salmonella Dublin has been increasingly isolated from diagnostic laboratory samples. The objective of this observational cross-sectional study was to identify management practices associated with herd positivity for Salmonella Dublin. A convenience sample of 100 dairy farms was visited in Ontario, Canada, from April to August 2022. Farms were visited once to collect blood samples from 20 heifers between 4 and 24 mo old, sample bulk tank milk, and administer an in-person questionnaire on management practices. An additional bulk tank milk sample was collected before the visit by milk transporters. All bulk tank and serum samples underwent ELISA testing to determine Salmonella Dublin positivity (≥35% positivity on ELISA). Of the 1,990 heifers sampled, 44 (2.2%) animals were seropositive for Salmonella Dublin. At least one seropositive heifer was identified on 24% of participating farms. Based on the bulk tank milk samples collected during both sampling periods, 4% of farms were positive for Salmonella Dublin. Overall, of the 100 farms visited, 25% were classified as Salmonella Dublin positive, meaning at least one serum or bulk tank sample was interpreted as positive. A multivariable logistic regression model identified 5 factors associated with herd-level positivity for Salmonella Dublin. Specifically, introducing purchased animals within the last 2 years increased the likelihood that farms were positive for Salmonella Dublin (odds ratio [OR] = 4.6). Farms that had at least one animal leave the premises for a cattle show, embryo collection center, or loan to another farm and return within the last 2 years were also at a higher risk for Salmonella Dublin (OR = 4.9). Farms that removed manure from the surface of bedding in calving pens twice per month or after every calving were at greater risk for Salmonella Dublin than farms that removed manure less frequently (OR = 8.5). Farms that added bedding material to calving areas once or twice weekly were at lower risk for Salmonella Dublin compared with farms that added bedding less than once weekly (OR = 0.1). In addition, farms that kept 3 cows or less per pen in the calving area were at lower risk for Salmonella Dublin. Test positivity for Salmonella Dublin among Ontario dairy farms sampled is high, and dairy producers should consider avoiding management practices that are associated with an increased risk of Salmonella Dublin infection.

Meta-analysis of the incidence of pregnancy losses in dairy cows at different stages to 90 days of gestation.

Pregnancy losses are a biological challenge and economically important in dairy herds. A meta-analysis was conducted to quantify losses in 4 periods from 19 to 90 d of pregnancy corresponding to the physiological development of gestation in dairy cows. A total of 19,723 diagnostic records from 46 studies were included. Pregnancy losses averaged 27%, 13%, 7%, and 2% in the early embryonic (19 to 32 d), late embryonic (30 to 45 d), early fetal (45 to 60 d), and later fetal (60 to 90 d) stages. These results provide a formal synthesis of the incidence of pregnancy losses in dairy cows.

Lack of evidence for Mycoplasma spp. in bulk tank milk of herds located in mid-western Colombia / Falta de evidencia para Mycoplasma spp. en leche de tanques de enfriamiento de hatos del centro-occidente colombiano

ABSTRACT Mycoplasma spp. is reported as a highly contagious mastitis-causing bacteria in dairy cattle, without successful or low response to most common antibiotic treatments due to the lack of cell wall. In Colombia it has been reported in the Central Andean region during 2014. The aim was to estimate the prevalence of Mycoplasma spp. in bulk tank milk using microbiological and molecular diagnosis. A random longitudinal study enrolling 220 commercial dairy farms located in four provinces of the mid-western region of Colombia from four pasteurizer companies was performed. Bulk tank milk samples were collected once monthly for three months period for determining somatic cell count (SCC) and microbiological and molecular diagnosis of Mycoplasma spp. cultures were done without pre-enrichment procedures directly in mycoplasma agar with cefoperazone to inhibit growth of opportunistic microorganisms, plates were incubated under 37° C and atmosphere of 10% CO2 and inspected during a 10d period. Molecular analysis was done by a multiplex PCR using specific primers targeting the 16S-23S rARN gene of Mycoplasma spp. and from non-pathogenic bacteria occasionally found in milk. LnSCC average of included dairy farms was 6.19 x103 cells/mL, Mycoplasma spp. was not isolated during microbiological cultures, and no DNA belonging to the species was detected by PCR in the 220 bulk tanks milk, with an estimated prevalence lower than 2.3%. This finding shows that there is not microbiological or molecular evidence that demonstrates the presence of the pathogen in the milk from the mid-western region of Colombia at herd level.

RESUMEN Mycoplasma spp. está descrito como una bacteria causante de mastitis altamente contagiosa en ganado lechero, sin o con baja respuesta a tratamientos antibióticos convencionales debido a que carece de pared celular. En Colombia ha sido reportado en la región Andina Central durante 2014. El objetivo fue estimar la prevalencia de Mycoplasma spp. en leche de tanques de enfriamiento empleando diagnósticos microbiológicos y moleculares. Se realizó un estudio aleatorio longitudinal que incluyó 220 lecherías comerciales en cuatro departamentos del centro-occidente colombiano acopiadas por cuatro compañías pasteurizadoras. Se recolectaron muestras de leche del tanque de enfriamiento mensualmente durante tres meses para determinar el recuento de células somáticas (SCC) y el diagnóstico microbiològico y molecular de Mycoplasma spp. Los cultivos se realizaron sin procedimientos de preenriquecimiento directamente en agar micoplasma con cefoperazona para inhibir crecimiento de microorganismos oportunistas, los agares se incubaron a 37° C con una atmosfera del 10% CO2 e inspeccionados durante 10d. Los análisis moleculares se realizaron por PCR multiplex usando cebadores específicos para los genes 16S-23S rRNA del Mycoplasma spp. y de algunas bacterias oportunistas ocasionales en la leche. El promedio del LnSCC fue de 6.19 x103 células/ mL, Mycoplasma spp. no fue aislado de los cultivos microbiológicos y no se encontró ADN de a esta especie mediante PCR en los 220 tanques de leche. Lo anterior indica una prevalencia estimada menor a 2,3%. Se concluye que no existe evidencia micro-biológica ni molecular para demostrar la presencia del patógeno en la leche de la región centro-occidente colombiana a nivel de hato.

Development and validation of a clinical respiratory disease scoring system for guiding treatment decisions in veal calves using a Bayesian framework.

Active infectious bovine respiratory disease (BRD) is an infection of the airways that needs to be diagnosed correctly so that appropriate treatment can be initiated. The simplest and most practical test to detect active BRD in dairy calves raised for veal is the detection and interpretation of clinical signs by producers or technicians. However, the clinical scoring system currently available for veal calves lacks sensitivity and specificity, contributing to economic losses and high use of antimicrobials. An accurate and reliable batch-level test to detect active BRD is essential to tailor antimicrobial use and reduce economic losses in veal calves. The objective of this study was therefore to develop and validate a new veal calf respiratory clinical scoring system (VcCRS), including reliable clinical signs (cough, ear droop or head tilt) and increased rectal temperature to detect active BRD in batches of veal calves housed individually, and to describe the accuracy of the scoring system for identifying batches of veal calves to treat. During 2017 to 2018, clinical examination, thoracic ultrasonography (TUS) and a haptoglobin concentration (Hap) were prospectively performed on 800 veal calves housed individually in Québec, Canada. Deep nasopharyngeal swabs were performed on 250 veal calves. A Bayesian latent class model accounting for imperfect accuracy of TUS and Hap was used to obtain weights for the clinical signs and develop the VcCRS. The VcCRS was then validated externally in 3 separate data sets. Finally, the applicability of the VcCRS at batch level was determined. We found that calves with 2 of the following findings-cough, unilateral or bilateral ear droop or head tilt, or increased rectal temperature ≥39.7°C-were considered positive and had a 31% chance of having active BRD. Without at least 2 of these 2 findings, a calf had a 100% chance of not having active BRD. At the batch level, we found that a batch with ≥3 positive calves among 10 calves sampled 2 wk after arrival at the fattening unit had a 94% chance of having an active BRD prevalence ≥10%. A batch with <3 positive calves had a 95% chance of not having an active BRD prevalence ≥10%. In this study, we developed a simple individual and batch-level score that is reliable across examiners and performs effectively in the detection of active BRD in veal calves. The implementation of this VcCRS in the veal calf industry would promote the elaboration of a protocol tailoring antimicrobial use.

Association between transfer of passive immunity and health disorders in multisource commingled dairy calves raised for veal or other purposes: Systematic review and meta-analysis.

Inadequate transfer of passive immunity (ITPI) in newborn dairy calves remains an important risk factor for mortality and morbidity. Most available studies are focused on calves delivered and raised on the same farms. This setting is far different from calves transported and commingled from different farms to be raised as veal or for other purposes. The aim of this systematic review and meta-analysis was to describe the association between ITPI and important health outcomes (mortality, bovine respiratory disease, and diarrhea) in multisource commingled dairy calves raised for veal or other purposes. We searched studies through CAB abstracts (via CAB direct), PubMed, and Web of Science (via ISI) databases until September 2, 2021. Observational studies and randomized trials written in English or French assessing ITPI association with any of the selected outcomes were included. Young dairy calves transported to commercial facilities and explicitly stated as being raised for veal production or not (then considered as "other") were our populations of interest. If raw or adjusted data were available for ≥5 studies for a given outcome of interest, then random effect meta-analysis models were used to investigate ITPI effects on this outcome. Nineteen studies were selected from 6,221 abstracts retrieved in the initial search. We observed significantly higher odds of mortality in calves with ITPI compared with those with successful transfer of passive immunity [odds ratio (OR) = 2.46; 95% confidence interval (CI): 1.43-4.22, n = 8 studies]. Calves with ITPI had higher odds of diarrhea (OR = 3.03; 95% CI: 1.2-7.62, n = 7 studies). A significant publication bias toward publishing studies with positive results was found in studies reporting on bovine respiratory disease (n = 5 studies), which revealed nonsignificant associations after correction of publication bias (OR = 1.40; 95% CI: 0.77-2.6). Heterogeneity could not be thoroughly investigated for mortality and diarrhea due to the limited number of studies. Therefore, the pooled estimates of the random models should be interpreted with caution despite their robustness to sensitivity analyses. In this study, we also observed that multiple definitions for transfer of passive immunity and outcomes were used in the literature. Moreover, the raising system definition was often limited. There seems, therefore, to be a need for standardized definitions of these parameters, as well as a better description of systems used for multisource commingled dairy calves raised for veal production or other production purposes.

Associations of calf management practices with antimicrobial use in Canadian dairy calves.

The objective of this cross-sectional study was to investigate the relationship between management practices and antimicrobial use in heifer calves on Canadian dairy farms. Questionnaires on calf management practices, herd characteristics, and calf treatment records were administered on 147 dairy farms in 5 provinces during annual farm visits in a multiyear, nationwide research project (Canadian Dairy Network for Antimicrobial Stewardship and Resistance: CaDNetASR). Questions focused on the calf caregiver, calving pen, colostrum management, milk feeding, grouping, bedding management, and age when male calves were sold. Antimicrobial treatment records were collected on each farm from either an electronic herd management system or paper-based records. Newborn heifers born in the last 12 mo were identified retrospectively and followed to 60 d of age, with antimicrobial treatments and dates of sale or death extracted for further analysis. A multivariable linear regression model was developed with the natural log of the number of antimicrobial treatments per calf-year as the dependent variable, and categorized calf management practices and farm characteristics as the independent variables. A complete data set of records on 7,817 calves was retrieved from 74 farms based on completeness of calf records. A total of 2,310 calves were treated at least once with an antimicrobial, and 7,307 individual antimicrobial treatments were recorded. Among the reasons for antimicrobial use, respiratory disease (54%) was most common, followed by diarrhea (20%), presence of a fever (3%), and umbilical disease (2%). Florfenicol (33% of recorded treatments), penicillin (23%), and trimethoprim-sulfamethoxazole (18%) were commonly used, whereas fluoroquinolones (4%), and ceftiofur (1%) were used less commonly. Farms (31%) commonly had 0-1.0 antimicrobial treatments/calf-year (median: 2.2 treatments/calf-year; interquartile range: 0.64-6.43 treatments/calf-year). Defined daily dose (DDD) per calf-year was calculated based on the Canadian bovine standards. Among the 74 farms, florfenicol (1.35 DDD/calf-year) and macrolides (0.73 DDD/calf-year) were used most, whereas ceftiofur (0.008 DDD/calf-year) was the lowest. The final multivariable linear regression model indicated that farms that fed transition milk had fewer than half the number of antimicrobial treatments per calf-year than those who did not feed transition milk. The number of antimicrobial treatments per calf-year in preweaning calves was low on many farms, and there was low use of highly important drugs for human medicine. The effect of feeding transition milk should be investigated regarding potential effects on antimicrobial use and disease prevention.

Bayesian estimation of sensitivity and specificity of a milk pregnancy-associated glycoprotein ELISA test for pregnancy diagnosis between 23 and 27 days after insemination in Holstein dairy cows.

Pregnancy diagnosis using pregnancy-associated glycoprotein (PAG) ELISA technology in blood or milk samples is validated from 28 d after insemination in dairy cows. The objective of this study was to estimate the sensitivity (Se) and specificity (Sp) of a commercial milk PAG-based ELISA in Holstein dairy cows between 23 and 27 d after insemination. Milk samples (n = 268) from 257 Holstein dairy cows 23 to 27 d after AI were submitted for PAG ELISA testing. Pregnancy status was confirmed by either a second milk PAG ELISA test conducted between 28 and 50 d after insemination (n = 200) or transrectal ultrasonography performed between 28 and 59 d after insemination (n = 68). A Bayesian latent class model was used to compare the paired results from the test at 23 to 27 d after AI test to the reference test. The latent class model typically used for comparing 2 or more imperfect tests was extended to include the possibility of pregnancy loss between the 23 to 27 d test and the reference test. Informative priors for the probability of pregnancy loss, and for the Se and Sp of the PAG and ultrasonography reference tests were obtained from the scientific literature. Estimated median Se and Sp of the PAG ELISA test conducted between 23 and 27 d after AI were 0.98 (95% credible interval 0.93 to 1.0) and 0.98 (0.89 to 1.0), respectively, when using a standardized corrected optical density threshold of 0.15. Although the accuracy of the test under investigation was excellent, more data will be needed to confirm the optimal diagnostic cut point for PAG in milk for early pregnancy diagnosis in this time window. The optimal timing of pregnancy diagnosis will depend on herd-specific logistics and the action to be taken to re-inseminate nonpregnant cows.

Effect of dry-off management on milking behavior, milk yield, and somatic cell count of dairy cows milked in automated milking systems.

Milk production may be reduced before dry-off to decrease the risk of cows developing intramammary infections during the dry period. Such reductions in milk may be possible in automated milking systems (AMS) where milking frequency and feed allocation at the AMS can be controlled at the cow level. This study investigated the effect of dry-off management of cows milked in AMS on milk yield, milking behavior, and somatic cell count (SCC). Using a 2 × 2 factorial arrangement of treatments, applied from d 14 to 1 before dry-off, 445 cows from 5 commercial dairy farms in Quebec, Canada, were assigned within farm to either (1) reduced feed [RF; allowed a maximum of 0.75 kg/d of AMS pellet for the first week (14 to 8 d before dry-off) of treatment, and 0.50 kg/d for the second week (7 to 1 d before dry-off) of treatment], or (2) nonreduced feed (NF; allowed up to 2 kg/d of AMS pellet), and either (1) reduced milking (RM; reduced to 2 milkings/d or as many times as required to yield 17 kg/milking), or (2) nonreduced milking (NM; allowed up to 6 AMS milkings/d) and no maximum production. Feed and milking behavior data, as well as milk yield and SCC were collected from the AMS software. The RF cows had lower AMS feed delivered during the treatment period, as per the experimental design. Across the treatment period, the NF-NM cows had the highest milking frequency (2.7 times/d), followed by the RF-NM cows (2.4 times/d), and then both of the RM groups (1.8 times/d), which did not differ from each other. All cows, except the NF-NM cows, were gradually milked less frequently as dry-off approached. Across the entire 2-wk treatment period before dry-off, cows with RM allowance experienced a higher reduction in milk yield compared with the cows with no milking allowance restrictions (-4.8 vs. -3.6 kg). Similarly, cows with a RF allocation tended to have a higher reduction in milk yield than cows with NF (-4.6 vs. -3.7 kg). As result, those cows with both reduced milking permissions and feed allocation at the AMS experienced the greatest drop in milk production before dry-off. There were no differences between treatments for milking frequency or yield in the next lactation. Somatic cell score (calculated from SCC) was not different between treatments in the 2-wk or day before dry-off, nor in the first month after calving. Overall, these data suggest that reducing both milking frequency and feed quantity in the AMS is the most efficient method to decrease milk yield before dry-off, without negatively influencing milking frequency or yield in the next lactation, as well as without affecting milk quality.

Evaluation of inter-rater agreement of the clinical signs used to diagnose bovine respiratory disease in individually housed veal calves.

In dairy calves raised for veal, typical clinical signs of bovine respiratory disease (BRD) are ocular discharge, nasal discharge, ear droop or head tilt, abnormal respiration, cough, and increased rectal temperature. Despite the existence of several clinical scoring systems, there are few studies on the variability of human recognition of individual BRD clinical signs. The objective of this study was therefore to assess the inter-rater agreement of BRD clinical signs in veal calves. We hypothesized that BRD clinical signs were not detected equally between veterinarians, technicians, and producers of the veal industry and that some clinical signs have higher inter-rater agreement than others. During 2017-2018, we prospectively recorded 524 videos of physical examinations of random veal calves from 48 different batches in Québec, Canada. A researcher, not involved in the inter-rater assessment, classified each video as presence/absence of each BRD clinical sign except rectal temperature. For each of the 5 clinical signs, 15 videos with and 15 videos without the clinical signs were randomly selected to avoid kappa paradoxes. Those 30 videos were then presented in a random order to experienced raters of BRD in veal calves: 6 veterinarians, 6 technicians, and 6 producers. The raters assessed the clinical signs using scores based on the Wisconsin and California scoring system with modifications (0 = absent, 1 = mild, 2 = moderate, 3 = severe for nasal discharge, ocular discharge, and ear droop or head tilt; and 0 = absent, 1 = moderate, 2 = severe for abnormal respiration and induced cough). We used median percentage agreement (Pa), median Cohen's kappa (κ), and Gwet's agreement coefficient 1 (AC1) to assess inter-rater agreement. The effect of scale combination was also tested to determine the optimal combination (4-scale 0/1/2/3 vs. 3-scale 0/1/2 vs. 2-scale 0/1,2,3; 0,1/2,3; or 0/1,2). The differences of inter-rater agreement between veterinarians, technicians, and producers were estimated by a Wilcoxon rank-sum test. The 2-scale combination (0,1/2,3 or 0/1,2) had the highest inter-rater agreement for all clinical signs. With this combination, induced cough was the clinical sign with the highest inter-rater agreement (Pa = 0.93; κ = 0.79; AC1 = 0.87) and abnormal respiration was the sign with the lowest inter-rater agreement (Pa = 0.77; κ = 0.20; AC1 = 0.74). According to Pa and AC1 values, the 2-scale inter-rater agreement of the 5 clinical signs was good (value > 0.6). According to κ, only ear droop or head tilt and induced cough had a substantial 2-scale inter-rater agreement (κ > 0.6). In general, the 2-scale inter-rater agreement was better among veterinarians than among technicians and producers, except for the ear droop/head tilt, where agreement was better among producers. We concluded that with severity scores assessed on a scale of 2 (0,1/2,3 or 0/1,2), the inter-rater agreement of BRD clinical signs was variable according to the sign in veal calves. BRD clinical signs were not detected equally between veterinarians, technicians, and producers of the veal industry. Future research could determine if this discrepancy could be improved by standardization training.

Bayesian latent class analysis when the reference test is imperfect.

Latent class analysis (LCA) has allowed epidemiologists to overcome the practical constraints faced by traditional diagnostic test evaluation methods, which require both a gold standard diagnostic test and ample numbers of appropriate reference samples. Over the past four decades, LCA methods have expanded to allow epidemiologists to evaluate diagnostic tests and estimate true prevalence using imperfect tests over a variety of complex data structures and scenarios, including during the emergence of novel infectious diseases. The objective of this review is to provide an overview of recent developments in LCA methods, as well as a practical guide to applying Bayesian LCA (BLCA) to the evaluation of diagnostic tests. Before conducting a BLCA, the suitability of BLCA for the pathogen of interest, the availability of appropriate samples, the number of diagnostic tests, and the structure of the data should be carefully considered. While formulating the model, the model's structure and specification of informative priors will affect the likelihood that useful inferences can be drawn. With the growing need for advanced analytical methods to evaluate diagnostic tests for newly emerging diseases, LCA is a promising field of research for both the veterinary and medical disciplines.

L'analyse à classes latentes a permis aux épidémiologistes de surmonter les problèmes concrets posés par les méthodes traditionnelles d'évaluation des essais de diagnostic, qui nécessitent à la fois un test de référence absolue (étalon ou gold standard) et un grand nombre d'échantillons de référence aux caractéristiques appropriées. Au cours des quatre dernières décennies, les méthodes d'analyse à classes latentes ont acquis de l'ampleur et permettent aux épidémiologistes d'évaluer les essais diagnostiques et d'estimer les taux de prévalence réelle tout en recourant à des tests supposés imparfaits, grâce à l'utilisation de données et de scénarios divers et complexes, y compris dans les situations d'émergence de nouvelles maladies infectieuses. Les auteurs font un tour d'horizon des dernières évolutions dans ce domaine et donnent des orientations pratiques concernant la manière d'utiliser l'analyse bayésienne à classes latentes pour évaluer les performances d'un test de diagnostic. Avant de conduire une telle analyse, il convient de déterminer avec soin si elle est adaptée à l'agent pathogène considéré et si les échantillons disponibles sont appropriés et en nombre suffisant ; il convient également de prendre en compte le nombre de tests de diagnostic à évaluer et la structure des données utilisées. Lors de la conception du modèle, sa structure et la définition préalable des données informatives vont affecter la probabilité que le modèle génère des inférences utiles. Face à la nécessité croissante de disposer de méthodes analytiques sophistiquées pour évaluer les tests de diagnostic utilisés pour les maladies émergentes nouvelles, les analyses à classes latentes offrent des perspectives prometteuses pour la recherche, aussi bien dans le domaine de la santé vétérinaire que de la médecine humaine.

El análisis de clases latentes ha servido a los epidemiólogos para superar las limitaciones prácticas que imponen los métodos tradicionales de evaluación de pruebas de diagnóstico, que requieren a la vez una prueba de diagnóstico que sirva de patrón de referencia perfecto y un gran número de muestras de referencia adecuadas. En los últimos cuatro decenios, los métodos de análisis de clases latentes se han ido ampliando hasta permitir a los epidemiólogos evaluar pruebas de diagnóstico y calcular la prevalencia real empleando pruebas imperfectas ante muy diversas estructuras de datos y situaciones complejas, incluida la aparición de nuevas enfermedades infecciosas. Los autores, tras presentar a grandes líneas los últimos adelantos en cuanto a métodos de análisis de clases latentes, ofrecen indicaciones prácticas para aplicar el análisis bayesiano de clases latentes a la evaluación de pruebas de diagnóstico. Antes de proceder a un análisis bayesiano de este tipo conviene estudiar con detenimiento la idoneidad del método para el patógeno en cuestión, la disponibilidad de muestras apropiadas, el número de pruebas de diagnóstico y la estructura de los datos. A la hora de formular el modelo, la estructura del propio modelo y la especificación de los elementos informativos previos influirán en la probabilidad de poder extraer conclusiones provechosas. Ante la creciente necesidad de disponer de métodos analíticos avanzados con los que evaluar pruebas de diagnóstico de nuevas enfermedades emergentes, el análisis de clases latentes abre un promisorio campo de investigación para las disciplinas veterinarias y médicas.

Accuracy of direct and indirect methods for assessing bovine colostrum quality using a latent class model fit within a Bayesian framework.

Feeding high-quality colostrum is essential for calf health and future productivity. Therefore, accurate assessment of colostrum quality is a key component of dairy farm management plans. Direct and indirect methods are available for assessment of colostrum quality; however, the indirect methods are rapid, inexpensive, and can be performed under field settings. A hierarchical latent class model fit within a Bayesian framework was used to estimate the sensitivity (Se) and specificity (Sp) of the radial immunodiffusion (RID) assay, transmission infrared (TIR) spectroscopy, and digital Brix refractometer for the assessment of low-quality bovine colostrum in Atlantic Canada dairy herds. The secondary objective of the study was to describe the distribution of herd prevalence of low-quality colostrum. Colostrum quality of 591 samples from 42 commercial Holstein dairy herds in 4 Atlantic Canada provinces was assessed using RID, TIR spectroscopy, and digital Brix refractometer. The accuracy of all tests at different Brix value thresholds was estimated using Bayesian latent class models to obtain posterior estimates [medians and 95% Bayesian credibility intervals (95% BCI)] for each parameter. Using a threshold of <23% for digital Brix refractometer and <50 g/L for RID and TIR spectroscopy, median (95% BCI) Se estimates were 73.2 (68.4-77.7), 86.2 (80.6-91.0), and 91.9% (89.0-94.2), respectively. Median (95% BCI) Sp estimates were 85.2% (81.0-88.9) for digital Brix refractometer, 99.4% (97.0-100) for RID, and 90.7% (87.8-93.2) for TIR spectroscopy. Median (95% BCI) within-herd low-quality colostrum prevalence was estimated at 32.5% (27.9-37.4). In conclusion, using digital Brix refractometer at a Brix threshold of <23% could reduce feeding of low-quality colostrum to calves and improve colostrum and calf management practices in Atlantic Canada dairy herds. The TIR spectroscopy showed high Se in detection of low-quality colostrum. However, the RID assay, which is used as the reference test in several studies, showed limited Se for detection of low-quality colostrum.

An observational cohort study on antimicrobial usage on dairy farms in Quebec, Canada.

Quantification of antimicrobial usage (AMU) is crucial to measure the effect of intervention programs, to determine associations between usage and resistance, to compare populations, and for benchmarking purposes. The primary objective of the study was to describe quantitatively the AMU on Quebec dairy farms over 1 yr: (1) the total AMU, (2) the AMU per administration route (intramammary, injectable, oral, intrauterine), and (3) the AMU per antimicrobial class and according to the categorizations of Health Canada and the World Health Organization. The secondary objective was to assess the effect of several characteristics (herd size, level of milk production, and incidence rate of common infectious diseases) on AMU rate. The AMU data were obtained for 101 dairy farms randomly selected in 3 important Quebec dairy regions by collecting and recording all empty drug packaging and invoices for medicated feed (spring 2017 to spring 2018). The AMU rate was reported in number of Canadian defined course doses for cattle per 100 cow-years. The average herd size was 67 cows per farm, and 2/101 farms were certified organic. Overall, an estimated mean of 537 Canadian defined course doses for cattle/100 cow-years was observed. The intramammary route during lactation was the most frequently observed, followed, in decreasing order of usage, by oral route in the feed, intramammary route at drying-off, and injectable route. Oral (other than in animal feed) and intrauterine formulations were infrequently collected from the garbage cans. The 5 most frequently observed antimicrobial classes were, by decreasing order of usage, ionophores, penicillins, aminocoumarins, aminoglycosides, and polymyxins. Highest priority critically important antimicrobials as defined by the World Health Organization were mainly collected from intramammary formulations during lactation followed by injectable and drying-off intramammary formulations. The herd size was positively associated with the total AMU rate but not with the usage rate of highest priority critically important antimicrobials. Incidence of diseases along with preventive use of antimicrobials (drying-off and medicated feed with antimicrobials) explained 48% of the variance in total AMU rate.

Identification and stable expression of vitellogenin receptor through vitellogenesis in the European eel.

In teleosts, vitellogenin (Vtg) is a phospholipoglycoprotein synthesized by the liver, released into the blood circulation and incorporated into the oocytes via endocytosis mediated by the Vtg receptor (VTGR) to form the yolk granules. The VTGR is crucial for oocyte growth in egg-laying animals but is also present in non-oviparous vertebrates, such as human. The VTGR belongs to the low-density lipoprotein receptor superfamily (LDLR) and is also named very-low-density lipoprotein receptor (VLDLR). In this study, we identified and phylogenetically positioned the VTGR of a basal teleost, the European eel, Anguilla anguilla. We developed quantitative real-time PCR (qRT-PCR) and investigated the tissue distribution of vtgr transcripts. We compared by qRT-PCR the ovarian expression levels of vtgr in juvenile yellow eels and pre-pubertal silver eels. We also analyzed the regulation of ovarian vtgr expression throughout vitellogenesis in experimentally matured eels. The Vtg plasma level was measured by homologous ELISA experimental maturation. Our in silico search and phylogenetical analysis revealed a single vtgr in the European eel, orthologous to other vertebrate vtgr. The qRT-PCR studies revealed that vtgr is mainly expressed in the ovary and also detected in various other tissues such as brain, pituitary, gill, fat, heart, and testis, suggesting some extra-ovarian functions of VTGR. We showed that vtgr is expressed in ovaries of juvenile yellow eels with no higher expression in pre-pubertal silver eels nor in experimentally matured eels. This suggests that vtgr transcription already occurs during early pre-vitellogenesis of immature eels and is not further activated in vitellogenic oocytes. European eel Vtg plasma level increased throughout experimental maturation in agreement with previous studies. Taken together, these results suggest that vtgr transcript levels may not be a limiting step for the uptake of Vtg by the oocyte in the European eel.

Implant retention and high rate of treatment failure in hematogenous acute knee and hip prosthetic joint infections.

OBJECTIVES: Only few studies evaluated hematogenous prosthetic joint infections. We aimed to describe the characteristics of these infections and factors associated with management failure. METHODS: We selected hematogenously-acquired infections, defined by the occurrence of infectious symptoms more than a year after implantation among records of patients treated for hip and knee prosthetic joint infections at Montpellier University Hospital between January 2004 and May 2015. Failure was defined by death due to prosthesis-related infection, need for prosthesis removal in case of conservative treatment, or recurrence of infectious signs on a new prosthesis. RESULTS: Forty-seven patients with hematogenous prosthetic joint infection were included (33 knee infections and 14 hip infections). Infectious agents were streptococci (43%), Staphylococcus aureus (43%), Gram-negative bacilli (13%), and Listeria monocytogenes (2%). Thirty-one patients were initially treated with debridement and implant retention and 15 with prosthesis removal (three with one-stage surgery, 10 with two-stage surgery). The median duration of antibiotic therapy was 66.5 days. The overall failure rate was 52% (24/48), 71% (22/31) with implant retention strategy, 13% (2/15) with prosthesis removal, and 63% (12/19) in case of Staphylococcus aureus infection. Conservative treatment was appropriate (arthrotomy on a well-implanted prosthesis without sinus tract and symptom onset <21 days) in 13/31 patients (42%) with a failure rate still high at 69% (9/13). The only factor associated with failure was conservative surgical treatment. CONCLUSION: The high risk of failure of conservative treatment for hematogenous prosthetic joint infections should lead to considering prosthesis replacement as the optimal strategy, particularly with Staphylococcus aureus.

Gonadotropin-inhibitory hormone in teleosts: New insights from a basal representative, the eel.

Since its discovery in birds, gonadotropin-inhibitory hormone (GnIH) has triggered investigation in the other groups of vertebrates. In the present study, we have identified a single gnih gene in the European eel (Anguilla anguilla), a representative species of a basal group of teleosts (Elopomorphs). We have also retrieved a single gnih gene in Osteoglossomorphs, as well as in more recently emerged teleosts, Clupeocephala. Phylogeny and synteny analyses allowed us to infer that one of the two gnih paralogs emerged from the teleost-specific whole genome duplication (TWGD or 3R), would have been lost shortly after the 3R, before the emergence of the basal groups of teleosts. This led to the presence of a single gnih in extant teleosts as in other vertebrates. Two gnih paralogs were still found in some teleost species, such as in salmonids, but resulting from the additional whole genome duplication that specifically occurred in this lineage (4R). Eel gnih was mostly expressed in the diencephalon part of the brain, as analyzed by quantitative real-time PCR. Cloning of eel gnih cDNA confirmed that the sequence of the GnIH precursor encoded three putative mature GnIH peptides (aaGnIH-1, aaGnIH-2 and aaGnIH-3), which were synthesized and tested for their direct effects on eel pituitary cells in vitro. Eel GnIH peptides inhibited the expression of gonadotropin subunits (lhß, fshß, and common a-subunit) as well as of GnRH receptor (gnrh-r2), with no effect on tshß and gh expression. The inhibitory effect of GnIH peptides on gonadotropic function in a basal teleost is in agreement with an ancestral inhibitory role of GnIH in the neuroendocrine control of reproduction in vertebrates.

A qualitative study of Ontario dairy farmer attitudes and perceptions toward implementing recommended milking practices.

Recommended milking practices (RMP) are protective against mastitis. However, many producers do not adopt, or only partially adopt, these measures. This study aimed to explore the attitudes and perceptions of Ontario dairy farmers toward barriers to implementation of RMP and to investigate what motivates behavior change in relation to milking hygiene. Four focus groups with Ontario dairy producers were conducted, and verbatim transcripts were analyzed thematically. The main barriers to adoption of RMP were identified and categorized into 2 groups: intrinsic barriers and physical barriers. Intrinsic barriers included personal habits and convenience, not perceiving udder health as a priority on their farm, and lack of information. Physical barriers included employee training and compliance, convenience of implementing RMP, and time, money, and labor barriers. Producers used their bulk tank somatic cell count (SCC) as a measure of perceived severity of udder health problems on farm. Those with lower SCC were less likely to prioritize udder health compared with peers experiencing elevations in SCC. Lack of udder health problems translated for some producers into non-adoption of certain RMP, as they felt these practices were not needed unless a problem arose. Others felt motivated to implement more practices and work toward better udder health if such efforts translated into rewards for better-quality milk. Some producers perceived RMP as not meaningful or useful, seemingly due to a lack of education about the reasons behind RMP implementation. Understanding the importance of these practices is one key to implementing them. To overcome some of the intrinsic barriers, increased efforts in knowledge translation are needed, including efforts in retraining current practices, as well as in establishing best practices.

Mapping potential, existing and efficient wetlands using free remote sensing data.

Although wetlands remain threatened by human pressures and climate change, monitoring and managing them are challenging due to their high spatial and temporal dynamics within a fine-grained pattern. New satellite time-series at high temporal and spatial resolutions provide a promising opportunity to map and monitor wetlands. The objective of this study was to develop an operational method for managing valley bottom wetlands based on available free remote sensing data. The Potential, Existing, Efficient Wetlands (PEEW) approach was adapted to remote sensing data to delineate three wetland components: (1) potential wetlands, mapped from a digital terrain model derived from LiDAR data; (2) existing wetlands, delineated from land cover maps derived from Sentinel-1/2 time-series; and (3) efficient wetlands, identified from functional indicators (i.e. annual primary production, vegetation phenology, seasonality of carbon flux) derived from MODIS annual time-series. Soil and vegetation samples were collected in the field to calibrate and validate classification of remote sensing data. The method was applied to a 113 000 ha watershed in northwestern France. Results show that potential wetlands were successfully delineated (82% overall accuracy) and covered 21% of the watershed area, while 44% of existing wetlands had been lost. Small wetlands along headwater channels, which are considered as ordinary, cover 56% of wetland area in the watershed. Efficient wetlands were identified as contiguous pixels with a similar temporal functional trajectory. This method, based on free remote sensing data, provides a new perspective for wetland management. The method can identify sites where restoration measures should be prioritized and enables better understanding and monitoring of the influence of management practices and climate on wetland functions.